The present invention generally relates to air conditioning apparatus and, in a preferred embodiment thereof, more particularly relates to a charging hose assembly for adding refrigerant to an air conditioning refrigerant circuit from a canister containing pressurized refrigerant.
A common technique for adding a relatively small quantity of refrigerant to a refrigerant circuit of an air conditioning system, for example an automotive vehicle air conditioning system, is to interconnect a charging hose assembly between a suction line service fitting on the refrigerant circuit, and a small canister filled with pressurized refrigerant, and then flow at least some of the refrigerant from the canister into the circuit during operation of the system.
In one conventionally manufactured version thereof, the charging hose assembly includes (1) a length of refrigerant charging hose less than twelve inches long, (2) a piercing/dispensing shut-off valve connected to one end of the hose, and (3) a disconnect coupler fitting connected to the opposite end of the hose. To use the charging hose assembly, the shut-off valve is screwed onto a cylindrical outlet portion of the canister, and the coupler fitting is releasably locked onto the service fitting. When this is done, a fixed pin member within the coupler fitting depresses a corresponding opening pin within the service fitting to communicate the interior of the refrigerant circuit with the interior of the charging hose.
Next, the vehicle""s engine is started, and the air conditioning system is operated in its maximum cooling mode. A handle on the installed shut-off valve is then (1) rotated in a first direction to cause an associated valve stem portion of the valve to pierce the outlet portion of the canister, and then (2) rotated in the opposite direction to communicate the interior of the canister with the interior of the charging hose so that refrigerant flow from the canister into the refrigerant circuit is initiated.
To terminate the refrigerant charging process, the handle of the shut-off valve is rotated in its first direction to close the shut-off valve and thereby block the flow through the hose of any pressurized refrigerant remaining in the canister. The disconnect coupler fitting is then removed from the refrigerant circuit service fitting. If the canister has been completely emptied of refrigerant in this process, the shut-off valve is then removed from the canister and the empty canister is discarded.
A potential problem exists in this refrigerant charging technique when a conventionally constructed charging hose is utilizedxe2x80x94namely, the possibility that pressurized refrigerant will be undesirably discharged from the canister to the atmosphere if the above-described sequence is not precisely followed. This undesirable discharge of refrigerant to atmosphere can occur if, for example, the disconnect coupler fitting is removed from the service fitting before the shut-off valve is closed. If this is inadvertently done, any remaining pressurized refrigerant in the canister will simply be discharged to atmosphere through the removed disconnect coupler fitting. it is to this problem that the present invention is primarily directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a specially designed refrigerant charging hose assembly is provided which comprises a length of refrigerant charging hose having first and second ends, a shut-off valve secured to the first hose end, and a uniquely configured disconnect coupler fitting secured to the second end of the charging hose. The shutoff valve is releasably connectable to an outlet portion of a pressurized refrigerant storage canister, and the disconnect coupler fitting is releasably connectable to a refrigerant circuit service fitting having a depressible opening pin portion. In a first illustrated embodiment of the charging hose assembly the shut-off valve is representatively a threaded stem piercing/dispensing type shut-off valve, and in another illustrated embodiment of the charging hose assembly the shut-off valve is representatively a push-button type aerosol can actuator valve.
According to a primary aspect of the invention, the disconnect coupler fitting includes control means for (1) depressing the service fitting opening pin and permitting refrigerant flow through the disconnect coupler fitting, in response to connection of the disconnect coupler fitting to the service fitting, and (2) precluding refrigerant flow through the disconnect coupler fitting in response to removal of the disconnect coupler fitting from the service fitting. when the charging hose assembly incorporates a piercing/dispensing type shut-off valve at its canister end, even if a user of the charging hose assembly forgets to close the shut-off valve before removing the disconnect coupler fitting from the service fitting, remaining pressurized refrigerant in the canister will not be discharged to the atmosphere through the disconnect coupler fitting when it is removed from the service fitting. When the push-button type shut-off valve is used at the canister end of the charging hose assembly, this desirable feature of the disconnect coupler fitting is augmented by the canister shut-off valve which terminates refrigerant outflow from the canister when the valve""s push button is released.
Representatively, the disconnect coupler fitting control means include a control structure floatingly carried within a generally tubular body portion of the disconnect coupler fitting for axial movement relative thereto between (1) a first or closed position in which the control structure sealingly engages a seal structure within the coupler fitting body and precludes refrigerant through therethrough, and (2) a second or open position in which the control structure is moved away from the seal structure and permits refrigerant flow through the coupler fitting body. In a preferred embodiment thereof, the control structure includes a pin portion which engages and depresses the opening pin of the service fitting when the coupler fitting is connected the service fitting, the forcible engagement between these two pin portions shifting the control structure to its second position.
The seal structure is representatively a single annular resilient seal member which is captively and stationarily retained within the body portion, with the body portion refrigerant flow passage extending through the interior of the annular seal member. when the disconnect coupler fitting is installed on the service fitting the service fitting body is brought into sealing engagement with the seal structure. Thus, the single stationary seal member is sealingly contactable by both the service fitting and the floating control structure.
A spring structure resiliently biases the control structure toward its first or closed position. Accordingly, when the two pin portions are disengaged as the coupler fitting is being removed from the service fitting, the control structure is automatically spring-driven back to its first or closed position to preclude pressurized refrigerant from the canister from being forced outwardly through the removed coupler fitting in the event that the canister shut-off valve is inadvertently left or held in its open position with pressurized refrigerant remaining in the canister.
According to another feature of the invention, the hollow body portion of the disconnect coupler fitting is of a plastic material, and the control structure is of a metal construction. Representatively, the hollow body portion of the disconnect coupler fitting is configured for operative engagement with an R134a refrigerant circuit service fitting.